Area Forecast Discussion
Issued by NWS Medford, OR

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FXUS66 KMFR 222202

Area Forecast Discussion
National Weather Service Medford OR
302 PM PDT Fri Sep 22 2017

.DISCUSSION...The sky is clearing in areas west of the Cascades
but cloudy sky remains to the east. Expect clearing on the east
side tonight and below freezing temperatures are still expected in
the Klamath and Tulelake basins. A freeze warning and frost
advisory continues for those two areas, but this will be the last
issuance for the year as areas east of the Cascades have gone
through a deep freeze. There are still pockets in the valleys west
of the Cascades where low temperatures tonight will be in the
frost range and patchy frost can be expected in rural valleys east
of Medford, as well as eastern Douglas County, and the
Scott/Shasta Valleys in Siskiyou County. Part of the Klamath River
Valley near Oak Knoll could also see overnight temperatures in the
middle 30s.

A warming and drying trend is on track starting Saturday that is
expected to continue at least through the middle of next week.
High temperatures in the western valleys will still be a few
degrees below normal Saturday, warming to around normal on Sunday
then warming to about 5 degrees above normal early next week. At
the coast the thermal trough is starting to form with offshore
northeast to east winds already starting to appear at the upper
slopes. This could present a fire weather concern with a warm and
dry offshore winds at night but condition is not expected to be
as strong as in recent offshore events. The GFS model show the
thermal trough area expanding north into the Coos Bay area around
Wednesday. If this scenario verifies, North Bend and Coos Bay
could be quite warm during the middle of next week.

A weak front could move through the area around Friday. With each
run the GFS is showing this system to be weaker with the ECMWF
barely indicating any changes. We are keeping the forecast dry
through the end of next week with some increase in clouds on
Friday. The next chance for rain may not be until the first or
second week of October. /FB


.AVIATION...22/18Z TAF CYCLE...Morning fog in West Side valleys has
started clearing, but will take some time to do so, and some
locations in the Umpqua basin may make it into early afternoon
before VFR returns. MVFR and localized IFR will likely return west
of the Coastal ranges this evening, and to the Umpqua and perhaps
Illinois/Lower Rogue valleys overnight. Elsewhere, generally VFR
conditions are expected through the next 24 hours. BPN


.MARINE...Updated 245 PM PDT Friday, 22 September 2017...Short period
northwest swell will gradually diminish late tonight through
Saturday. However, a thermal trough will bring gusty north winds and
areas of steep seas south of Cape Blanco. Winds and seas south of
Cape Blanco will peak around 20 to 25 kt each afternoon and evening
through early next week. Through Saturday, steep seas will be a mix
of short period northwest swell and wind waves. Swell will diminish
Saturday night then north winds are expected to increase slightly
Sunday and Monday afternoon with small craft winds and seas south of
Cape Blanco. On Tuesday, winds may increase further with a mix of
small craft and gales possible by late Tuesday afternoon and Tuesday
evening. This may bring small craft conditions north of Cape Blanco
late Tuesday with a mix of gales and small craft conditions possible
south of Cape Blanco. North winds will lower Wednesday into
Wednesday night. -CC


OR...Frost Advisory from 2 AM to 9 AM PDT Saturday for ORZ029.
     Freeze Warning from 2 AM to 9 AM PDT Saturday for ORZ029.

CA...Frost Advisory from 2 AM to 9 AM PDT Saturday for CAZ084.
     Freeze Warning from 2 AM to 9 AM PDT Saturday for CAZ084.

Pacific Coastal Waters...Small Craft Advisory until 5 PM PDT Tuesday for PZZ356-376.


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